Use patents as described are very valuable and very common. And have been held up in court cases for many years now. You may not agree with the concept but they do exist. The key is the phrase "nonobvious" use of the object. You could never get a patent on the use of a screwdriver to open a paint can as it would be obvious to someone "skilled in the art" (which, in this case, is anyone who has ever opened a paint can). But using a known substance as a new paint additive can be nonobvious.
As an example (which I'm making up as I have no idea what goes into paint), say you discovered that adding baking soda to latex paint makes the paint stick to the wall better. No one has ever added a salt like this to paint before. You can get a claim to the use of baking soda as a paint additive (and probably one to a latex paint containing baking soda as well. You can claim the same concept several ways.) Yes, someone could buy baking soda and add it to paint at home and no one would really stop them. But if they sell paint containing baking soda they are infringing. Or if a large commercial company advertises that their paint jobs last longer because they add baking soda to their paint, they are infringing and are likely to get sued.
To make it even more complicated, say Dean Kamen has a patent claiming baking soda as a new composition. You can still get a claim to the use of baking soda in paint, but you can't sell that paint unless you get a license from Dean to sell something containing baking soda.
As for inventor resources, also check out the US Patent Office web site - they have a section for would-be inventors:
http://www.uspto.gov/web/offices/com/iip/index.htm
P.S. Shameless plug here. Patent agents can also write and prosecute patents for inventors, but since they are not attorneys they charge less. They have to have the same credentials as attorneys (i.e. minimum BS in some technical field) and have to pass the same patent bar as attorneys. They just can't do trademark work or litigation. A lot of them are scientists/engineers with many years research experience before they became patent agents. Or are former patent examiners, but I won't go into that.